fix(hooks,email): add describe_counter! to pre-register metrics

Hook tasks and email metrics were missing from /metrics because
describe_counter! was never called before install_recorder(), so
unincremented counters were not exported. Room metrics appeared
because RoomMetrics::new() already described them.

- apps/git-hook: describe 8 hook_tasks_*/hook_sync_* counters
- apps/email: describe 8 email_* counters
- both: add metrics = "0.22" as direct dependency

Cargo.lock

@@ -2538,6 +2538,7 @@ dependencies = [
  "config",
  "db",
  "hyper 0.14.32",
+ "metrics",
  "metrics-exporter-prometheus",
  "observability",
  "sea-orm",
@@ -3130,6 +3131,7 @@ dependencies = [
  "db",
  "git",
  "hyper 0.14.32",
+ "metrics",
  "metrics-exporter-prometheus",
  "observability",
  "reqwest 0.13.2",

apps/email/Cargo.toml

@@ -29,6 +29,7 @@ chrono = { workspace = true, features = ["serde"] }
 hyper = { workspace = true }
 serde_json = { workspace = true }
 sea-orm = { workspace = true }
+metrics = "0.22"
 metrics-exporter-prometheus = "0.13"
 
 [lints]

apps/email/src/main.rs

@@ -1,5 +1,6 @@
 use clap::Parser;
 use config::AppConfig;
+use metrics::{describe_counter, Unit};
 use metrics_exporter_prometheus::PrometheusHandle;
 use observability::{init_tracing_subscriber, install_recorder};
 use sea_orm::ConnectionTrait;
@@ -64,6 +65,17 @@ async fn main() -> anyhow::Result<()> {
     let args = Args::parse();
     let cfg = AppConfig::load();
     init_tracing_subscriber(&args.log_level, false);
+
+    // Pre-register all email/queue metrics so they appear in /metrics even before first event.
+    describe_counter!("email_queued_total", Unit::Count, "Emails written to Redis stream");
+    describe_counter!("email_consumed_total", Unit::Count, "Emails consumed from queue");
+    describe_counter!("email_batch_size", Unit::Count, "Email consumer batch sizes accumulated");
+    describe_counter!("email_validation_skipped_total", Unit::Count, "Emails skipped due to invalid recipient");
+    describe_counter!("email_build_errors_total", Unit::Count, "Email message build failures");
+    describe_counter!("email_send_attempts_total", Unit::Count, "SMTP send attempts (including retries)");
+    describe_counter!("email_sent_total", Unit::Count, "Emails sent successfully");
+    describe_counter!("email_send_failures_total", Unit::Count, "Emails that failed after all retries");
+
     let metrics_handle = Arc::new(install_recorder());
 
     tracing::info!("Starting email worker");

apps/git-hook/Cargo.toml

@@ -26,6 +26,7 @@ tokio-util = { workspace = true }
 hyper = { workspace = true }
 serde_json = { workspace = true }
 sea-orm = { workspace = true }
+metrics = "0.22"
 metrics-exporter-prometheus = "0.13"
 chrono = { workspace = true, features = ["serde"] }
 reqwest = { workspace = true }

apps/git-hook/src/main.rs

@@ -3,6 +3,7 @@ use config::AppConfig;
 use db::cache::AppCache;
 use db::database::AppDatabase;
 use git::hook::HookService;
+use metrics::{describe_counter, Unit};
 use metrics_exporter_prometheus::PrometheusHandle;
 use observability::{init_tracing_subscriber, install_recorder};
 use sea_orm::ConnectionTrait;
@@ -66,6 +67,17 @@ async fn main() -> anyhow::Result<()> {
     // 2. Init tracing + metrics
     let log_level = cfg.log_level().unwrap_or_else(|_| "info".to_string());
     init_tracing_subscriber(&log_level, false);
+
+    // Pre-register all hook metrics so they appear in /metrics even before first increment.
+    describe_counter!("hook_tasks_total", Unit::Count, "Total hook tasks dequeued");
+    describe_counter!("hook_tasks_success_total", Unit::Count, "Hook tasks completed successfully");
+    describe_counter!("hook_tasks_failed_total", Unit::Count, "Hook tasks that failed");
+    describe_counter!("hook_tasks_locked_total", Unit::Count, "Hook tasks re-queued due to repo lock");
+    describe_counter!("hook_tasks_retried_total", Unit::Count, "Hook tasks that entered retry");
+    describe_counter!("hook_tasks_exhausted_total", Unit::Count, "Hook tasks that exhausted retries");
+    describe_counter!("hook_sync_branches_changed_total", Unit::Count, "Branches changed during sync");
+    describe_counter!("hook_sync_tags_changed_total", Unit::Count, "Tags changed during sync");
+
     let metrics_handle = Arc::new(install_recorder());
 
     // 3. Connect to database